基于零序电压柔性控制的配电网接地故障消弧与保护新原理

In order to solve the problems of over-voltage, arc extinguishing and protection for single-phase grounding faults in distribution networks, a novel zero sequence voltage flexible control method, fault arc extinguishing and ground protection theories with active voltage control are built with the idea reference of static synchronous compensator (STATCOM) in this project. The work mechanism of the injecting zero-sequence current to zero sequence voltage is analyzed; the grounding faults dynamic identification method, arc extinguishing and faults protection principle are proposed; new methods for over-voltage suppression techniques and grounding faults protection are invented. In the normal operation condition of distribution networks, zero sequence current will be injected by PWM inverter to compensate the unbalanced three-phase current, absorb the transient zero-sequence energy and suppress the zero-sequence over-voltage. On the initial stage of grounding faults, zero sequence current will be injected to control the zero sequence voltage and restrain the fault point voltage to zero, and the fault point current will also be restrained to zero, the ground fault arc can thus be 100% extinguished. After a delay, the injection current is superposed with a measurement signal. The magnitude, frequency and phase of the signal are optimally controlled, and the fault characteristic parameters are accurately measured, the grounding faults dynamic protection and location can be realized. Finally, zero sequence voltage flexible control and protection algorithms are designed and the principle prototype is also developed. The new theories and techniques can improve power quality, extinguish grounding faults arc, and increase the sensitivity and reliability of grounding faults protection.

为解决中性点非有效接地配电网长期存在的过电压、单相接地故障消弧与接地保护难题，借鉴电能质量控制领域的静止同步补偿器（STATCOM）思想，建立零序电压柔性控制及接地故障有源电压消弧与接地保护新理论。揭示注入零序电流对零序电压的作用机理，提出接地故障的动态辨识方法及消弧与保护新原理。发明过电压抑制和接地故障处理新方法：在配电网正常运行时，基于PWM有源逆变注入零序电流，补偿三相不平衡电流，吸收暂态零序能量，抑制零序过电压；在接地故障初始时间，注入零序电流，控制零序电压，强迫故障点电压为零，使故障残流为零，实现瞬时故障100%消弧；接地故障一定延时后，在注入电流中叠加测量信号，优化控制信号大小、频率和相位，精确测量故障特征参数，实现永久性故障的动态感知和保护与定位。并研究零序电压柔性控制及故障保护与定位算法，完成原理样机研制。有望改善配电网电能质量，降低故障建弧率，提高接地保护灵敏度和可靠性。

为解决中性点非有效接地配电网长期存在的过电压、单相接地故障消弧与接地保护难题，借鉴电能质量控制领域的静止同步补偿器（STATCOM）思想，建立了零序电压柔性控制及接地故障有源电压消弧与接地保护新理论；揭示了注入零序电流对零序电压的作用机理，建立零序电压柔性控制理论；揭示了单相接地故障消弧机理，建立有源电压消弧理论；提出了接地故障的动态辨识方法及消弧与保护新原理。发明了过电压抑制和接地故障处理新方法：在配电网零序电压波动时，通过注入配电网信号，谐振测量配电网阻尼率等零序参数，以此判断三相不平衡状态与故障状态；在配电网三相不平衡条件下，基于PWM有源逆变注入零序电流，补偿三相不平衡电流，抑制零序过电压；在配电网铁磁谐振过程中，注入零序电流，吸收暂态零序能量，抑制铁磁谐振过电压；在接地故障初始时间，注入零序电流，补偿故障无功电流、有功电流和谐波电流的故障点全电流，控制零序电压，强迫故障点电压为零，则故障残流为零，实现瞬时故障100%消弧；接地故障一定延时后，在注入电流中叠加测量信号，优化控制信号大小、频率和相位，精确测量故障特征参数，实现永久性故障的动态感知和保护与定位。并研究了零序电压柔性控制及故障保护与定位算法，提出多种闭环控制策略，完成原理样机和工程样机的研制。建设了10kV配电网和10公里电缆线路，完成样机的仿真分析和试验测试，验证了原理方法的可行性。保护技术已在电网运行，有源消弧技术已完成试验，正准备在电网测试，结果表明：该理论技术能有效改善配电网电能质量，降低故障建弧率，提高接地保护灵敏度和可靠性。.项目成果已获湖南省科技进步一等奖1项；在国内外进行高层次学术报告20余次；发表相关论文32篇，其中期刊论文19篇、SCI检索5篇、EI检索20篇；获发明专利6项、申请待批准的发明专利7项；培养博士毕业1人、在读2人，培养硕士毕业16人、在读8人；指导研究生获中国“互联网+”大学生创新创业大赛金奖1项、银奖1项；研究成果超过计划书中的预期目标。